1. Field
Apparatuses and methods consistent with exemplary embodiments relate to a light emitting diode (LED) driver circuit and a method of driving an LED, and more particularly, to an LED driver circuit having a low return current in a dimming mode and a method of driving an LED.
2. Description of the Related Art
Liquid crystal displays (LCDs) are thin and heavy and have a lower driving voltage and power consumption as compared with other display devices and thus, have been widely used. However, since the LCDs are non-emitting devices which cannot emit light, separate backlights are necessary to supply light to LCD panels.
As a light source for the backlight of the LCD, cold cathode fluorescent lamp (CCFL), LED, and the like are often used. However, CCFLs have drawbacks. Since the CCFL uses mercury, the CCFL may cause environmental pollution. Further, CCFL has a low response time and lower reproducibility. Thus CCFL is not appropriate for constructing lighter and thinner LCD panels.
On the contrary, since LEDs do not use an environment pollution material, LEDs are environmentally-friendly and capable of impulse driving. LEDs have advantages for the sort of lightness and thinness required in a modern LCD panel. Furthermore, with LEDs, luminance, color temperature, or the like, may be arbitrarily changed by adjusting a light intensity of red, green, and blue LED. As a result, LEDs are being widely employed as a light source for a backlight of the LCD panel (or the like) in recent years.
Thus, in a backlight of an LCD employing LEDs, a current supplied to an LED is varied corresponding to brightness information of an image to improve picture quality and reduce power consumption. Specifically, the current supplied to the LED is varied using a pulse width modulation (PWM) method and a pulse amplitude modulation (PAM) method.
However, in an LED driver circuit of the related art, even when a PWM signal is in a off state, a high current is maintained within the driver circuit so that conduction loss of the circuit is increased, thus causing excessive component heat. Further, in the LED driver circuit of the related art, when a gradation of an image is changed by a large amount, there is a case where a current supplied to the LED is overshot (i.e., exceeds a target value). As a result, flickering appears and a color gamut of the LED is not dynamically changed.